1. Field of the Invention
The present invention relates to an IC having shared pins, and more particularly, to an IC having shared pins that is able to control a display module and more than one circuit module externally coupled to the IC.
2. Description of the Prior Art
As electronic products are increasingly developed to be light, thin, short and small, electronic elements inside these electronic products should be of small size and weight for decreasing the internal space of electronic products occupied by these electronic elements.
Typically, microminiaturization of some electronic elements relies on the progression and development of semiconductor processes. Continually downsizing electronic elements, however, will result in a bottleneck. As well as microminiaturization of electronic elements, integrating several chips within an IC package (System in a Package, SiP) or arranging several circuits in a single IC (System on Chip, SoC) are other choices for downsizing electronic elements. These options usually involve several different circuits, which require pins for connecting to external electronic elements/devices, in either a SoC or a SiP. As the complexity of circuitry inside an IC packages increases, pin count of the IC package also increases.
In modern electronic products, such as PCs, portable media players or even thumb drives with an LCD panel (for displaying file names and storage status), display modules and memory modules are indispensable parts. Due to the popularity of these two circuit modules, the corresponding control modules are considered as the objects of microminiaturization. For example, by means of Soc or Sip, the above-mentioned two kinds of control modules can be implemented within one IC package. In smaller electronic products like portable media players and thumb drives, a liquid crystal display (LCD) is usually utilized as a display apparatus, and a micro hard disk or a flash memory module is utilized as a data storage apparatus. Thus, the following description utilizes “LCD display module” and “flash memory module” for illustration and ease of understanding.
In the prior art, different pin allocations for an IC having control modules for both a display apparatus and a memory apparatus are shown in FIG. 1 and FIG. 2, respectively.
As shown in FIG. 1, an IC 100 (an IC package) includes a data access control module (that is, a flash memory control module 110) and a display control module (that is, an LCD control module 120). The flash memory control module 110 and the LCD control module 120 both possess their own control signal pins 111, 121 and data signal pins 112, 122 for electrically connecting a memory module (a flash memory module 130) and a display module (an LCD display module 140), respectively.
Furthermore, an IC 200 shown in FIG. 2 also includes a flash memory control module 210 and an LCD display control module 220. Unlike the control modules shown in FIG. 1, the flash memory control module 210 and the LCD display control module 220 utilize a same pair of control and data signal pins 211, 212 to electrically connect a flash memory module 230 and an LCD display module 240. Compared to the IC 100 shown in FIG. 1, the IC 200 shown in FIG. 2 has a smaller pin count, thereby decreasing the size of the wiring board and the IC package, and even the power consumption.
According to the NTSC (National Television System Committee) standard, a refresh rate is 60Hz, which means that the LCD display control modules 120 and 220 have to finish a frame refresh operation within 1/60th of a second. Thus, the LCD display control modules 120 and 220 have to transmit data and control signals to the LCD display modules 140 and 240 for refreshing the LCD display modules 140 and 240 every 1/60th of a second. As shown in FIG. 2, under the condition that the control modules use shared pins, while the flash memory control module 210 is accessing the flash memory module 230, the refresh timing of the LCD display control module 220 may already have been reached. If the LCD display control module 220 cannot finish the data transmission to the LCD display module 240 before the refresh timing, some problems such as flickering or displaying faults may occur. To prevent the above-mentioned problems, there is usually a frame buffer disposed in a conventional LCD display module like the frame buffers 141 and 241 shown in FIG. 1 and FIG. 2. The frame buffers 1 41 and 241 can buffer the frame data for a next refresh timing by storing the frame data corresponding to the next 1/60th of a second into the frame buffers 141 and 241 in advance. Therefore, the condition that the LCD display control module has not yet transmitted the frame data is avoided.
However, allocating a frame buffer in the display module increases hardware cost thereof. Thus, the advantages of utilizing shared pins to decrease the pin count shown in FIG. 2 are cancelled out. As the control modules in the integrated circuit shown in FIG. 1 for controlling the display module and the memory module possess their own pins, the frame buffer in the display module is unnecessary. As a result, from the point of view of a designer, whether a display control module uses shared pins in an IC becomes a dilemma.